The present invention relates to a novel process for producing lysophospholipids containing substantially no lysophospholipids except lysophosphatidylcholine (LPC).
The lysophospholipid is obtained by the removal of one fatty acid unit per molecule from a phospholipid and the introduction of a hydroxyl group in place thereof. The lysophospholipid, being more highly hydrophilic than the phospholipid, not only has good emulsifying capability inherent in the phospholipid but is said to be capable of forming spherical micelles to solubilize water-insoluble substances in transparent state, and is therefore expected to be applicable as a solubilizer in the fields of food, cosmetics and drugs.
Heretofore, the lysophospholipids have been produced generally by causing an enzyme to act on natural phospholipids or phospholipid-containing substances derived from organisms or by subjecting these to alkali hydrolysis. The lysophospholipid thus obtained is ordinarily in the form of a mixture containing lysophospholipids such as lysophosphatidylethanolamine (LPE), lysophosphatidylinositol ( LPI) and lysophosphatidylserine (LPS) in addition to LPC.
Such a lysophospholipid mixture can per se be used as a natural surfactant or solubilizer but, when stored over a long period of time, turns gradually from ordinary pale yellow or white to brown and even gives out an unpleasant odor. Such a deterioration phenomenon has been found to become more notable as the content of lysophospholipids except LPC increases. Moreover, the higher the LPC content in the lysophospholipid, the more stable have emulsified or solubilized products obtained by using the lysophospholipid been found to be.
In view of the above, if lysophospholipids containing substantially no lysophospholipids except LPC could be produced, such products would be highly beneficial and valuable from a commercial point of view.
Since LPC is analogous to lysophospholipids except LPC in molecular structure and both of these lysophospholipids are surface active substances, the lysophospholipids except LPC cannot easily be removed from a lysophospholipid mixture by an ordinary simple substance separation method such as the solvent extraction method. Further, the removal from such a mixture is still more difficult because in respect of constituent fatty acids neither LPC nor the lysophospholipids except LPC comprise a single constituent fatty acid, but they have respectively specific compositions which are due to the starting materials.
While the removal of the target lysophospholipids is accompanied by the above described difficulties, the lysophospholipids except LPC can be removed with considerable accuracy, for example, by column chromatography with the use of silica gel or alumina at a laboratory level. It would be disadvantageous, however, to raise this level up to a commercial scale from the economic point of view including costs. Under such circumstances, an object of the present invention is to provide a process whereby lysophospholipids containing substantially no lysophospholipids except LPC can be produced on a commercial scale at low cost and yet by a simple procedure.